For the ultimate in iPhone 3GS protection and to take advantage of its camera function, you could get the Factron Quattro for iPhone SP, a case made from leather, carbon fiber, and stainless steel. The case is just under $200, and additional lenses like the fish-eye, wide angle, and macro zoom are about $15-50 each. I think this is only available in Japan though.
Product page (Thanks, Hitoshi!)



jesus that is ugly!
I kind of like it, although the screws make it look like a salt and pepper shaker.
i wanna buy this!